1. Field of the Invention
The present invention relates to a refrigerant compressor and, more particularly, to a valved discharge mechanism of a refrigerant compressor used in an automotive air conditioning system.
2. Description of the Prior Art
The valved discharged mechanism of a refrigerant compressor is well known in the prior art. For example, U.S. Pat. No. 4,226,572 discloses a structure and operational mechanism of a valved discharge mechanism in a refrigerant compressor. As disclosed therein, and referring to FIGS. 1 and 2 herein, a refrigerant compressor includes a cylinder block 1 comprised of a front cylinder block 1a and a rear cylinder block 1b. Further, the refrigerated compressor of FIGS. 1 and 2 includes front and rear housings 4a and 4b. Also provided are valve plates 3 located adjacent to each of the front cylinder block la and the rear cylinder block 1b. Valve plates 3 have a discharge hole 3a therethrough for selectively communicating the compression chamber with the discharge chamber. A discharge valve assembly includes discharge reed valve 21 and gasket 100 which are secured between valve plates 3 and housings 4a and 4b. Discharge reed valve 21, which is made of elastic material, regulates the flow of the refrigerant gas and makes sealing contact with one end of discharge hole 3a.
Gasket 100 includes radial ribs 107 arranged so as to be in alignment with discharge reed valve 21. Radial ribs 107 limit the bending movement of discharge reed valve 21 in the direction away from discharge hole 3a. Discharge reed valve 21 bends to block and open discharge hole 3a, and has a predetermined value of elastic modulus which allows discharge reed valve 21 to block the opening of discharge hole 3a until the pressure in the compression chamber 2 reaches a predetermined value.
In this arrangement, when the refrigerant compressor operates at high rotational speeds and/or under a high load, discharge reed valve 21 opens at a rapid rate until it comes in contact with curved portion 107a of radial rib 107. Curved portion 107a of radial rib 107 gradually deteriorates under the continued stress of this collision load. Eventually, the collisions cause radial rib 107 to be partially or fully broken or cracked. In the prior art, in order to prevent such breaking or cracking, the rigidity and/or thickness of the steel plate forming gasket 100 has been increased in order to reasonably bear these collisions. Even with a limited increase in rigidity and/or thickness of gasket 100, the life of gasket 100 is shortened. The durability of the compressor is thus decreased. Also, gasket 100 cannot be formed from nonferrous metals, such as aluminum or a thin steel plate which are produced at a low price, because gasket 100 is required to have a high rigidity.